JP5504306B2 - Control method of fuel cell system - Google Patents

Description

The present invention relates to a control method of a fuel cell system that supplies power to a load by a fuel cell and a power storage device. More specifically, the present invention relates to a control method of a fuel cell system that prevents deterioration or breakage due to excessive output of the fuel cell by controlling power supply to the load.

  A so-called hybrid power system that combines a plurality of power sources to supply power to a load is known (for example, Patent Document 1 and Patent Document 2). Patent Document 1 is a power system that combines a generator driven by an engine and a battery as a power storage device, and Patent Document 2 is a power system that combines a fuel cell and a power storage device.

  In Patent Document 1, the torque of the travel motor (load) is controlled so as not to exceed the sum of the maximum output of the battery and the actual output of the generator in order to prevent overdischarge of the battery (summary of Patent Document 1). reference).

JP 2000-166209 A JP 2005-166582 A

  In the case of a generator driven by an engine (that is, a mechanical power source) as described in Patent Document 1, electric power is supplied according to the engine speed. For this reason, even if the required output of the motor for driving the vehicle exceeds the supply power of the generator, the generator cannot supply more power. On the other hand, in the fuel cell as described in Patent Document 2, the supply power changes according to the required output of the motor (required power of the load) due to its output characteristics, and the required output of the motor is allowed by the fuel cell. When the maximum output (rated power) is exceeded, power exceeding the allowable maximum output is supplied. For this reason, depending on the required output of the motor, the fuel cell outputs excessive power, leading to deterioration or breakage of the fuel cell.

  In addition, the above contents are not limited to the case where the load is a motor for driving a vehicle, but also apply to other loads.

The present invention has been made in consideration of such problems, and an object of the present invention is to provide a control method for a hybrid fuel cell system that can prevent deterioration or breakage of the fuel cell.

  A fuel cell system according to the present invention includes a fuel cell that supplies power to a load, a power storage device that is connected to the load in parallel with the fuel cell and supplies power to the load, and the load and the power storage device. A voltage converter that changes the voltage between the fuel cell and the load by converting an output voltage of the power storage device, and controls power supplied from the fuel cell to the load; and A load control unit that controls power consumption of the load, wherein the load control unit controls the voltage between the fuel cell and the load when the voltage conversion unit is controlling the voltage between the fuel cell and the load. The power consumption of the load is limited to be equal to or less than the sum of the actual output of the power storage device or the maximum allowable output of the voltage converter, and the voltage converter is between the fuel cell and the load. Voltage is not controlled Come, and limits the actual power consumption of the load so that the sum following the output of the maximum allowable output and the power storage device or the voltage conversion unit of the fuel cell.

  According to the present invention, when the voltage conversion unit does not control the voltage between the fuel cell and the load, that is, when the power storage device or the voltage conversion unit may not output the allowable maximum output, The power consumption of the load is limited to be equal to or less than the sum of the maximum allowable output and the actual output of the power storage device or voltage converter. As a result, it is possible to prevent the fuel cell from compensating for the shortage of the output of the power storage device or the voltage conversion unit beyond its allowable maximum output, and to prevent deterioration or damage of the fuel cell. In addition, the output from the fuel cell and the power storage device or voltage are switched to switch the method of limiting the power consumption of the load depending on whether the voltage conversion unit controls the voltage between the fuel cell and the load or not. The output from the conversion unit can be suitably controlled.

  The load can be, for example, a vehicle driving motor. As a result, even when the voltage conversion unit does not control the voltage between the fuel cell and the load, the maximum electric power can be supplied from the fuel cell and the power storage device or the voltage conversion unit. It is possible to avoid such a reduction and improve drivability.

  The fuel cell system further includes an auxiliary device that receives power supply from between the motor and the fuel cell or the power storage device, and the load control unit includes a voltage converter between the fuel cell and the motor. When controlling the voltage of the load, the load is set to be equal to or less than the value obtained by subtracting the power consumption of the auxiliary machine from the sum of the actual output of the fuel cell and the allowable maximum output of the power storage device or the voltage converter. Or when the voltage converter does not control the voltage between the fuel cell and the motor, the allowable maximum output of the fuel cell and the actual power storage device or the voltage converter You may restrict | limit the power consumption of the said load so that it may become below the value which deducted the power consumption of the said auxiliary machine from the sum with an output. As a result, even when an auxiliary device that receives power supply from between the motor and the fuel cell or the power storage device is provided, the power consumption of the auxiliary device can be secured and the fuel cell and the power storage device can be more reliably protected. .

  The auxiliary machine may include an air compressor that supplies air to the fuel cell. As a result, the power consumption of the air compressor with relatively large power consumption can be secured, the air compressor can be driven stably, and the fuel cell and the power storage device can be more reliably protected.

  The load control unit, when the voltage conversion unit is controlling the voltage between the fuel cell and the load, or when not controlling the voltage between the fuel cell and the load, the fuel cell, If the actual output of the power storage device or the voltage converter is higher than the allowable maximum output, the power consumption of the load can be limited using the allowable maximum output instead of the actual output. Thereby, even if the actual output of the fuel cell, power storage device or voltage converter becomes transiently higher than the allowable maximum output, the fuel cell or power storage device can be protected.

A control method of a fuel cell system according to the present invention includes a fuel cell that supplies power to a load, a power storage device that is connected to the load in parallel with the fuel cell and supplies power to the load, and consumption of the load A load control unit that controls electric power, wherein the load control unit does not control a voltage between the fuel cell and the load, and is closer to the power storage device than the load. When the current or voltage is controlled, the allowable maximum output of the fuel cell is calculated, the actual output of the power storage device is calculated, and the sum of the allowable maximum output of the fuel cell and the actual output of the power storage device is calculated. And the power consumption of the load is limited to be equal to or less than the sum of the allowable maximum output of the fuel cell and the actual output of the power storage device.

  According to the present invention, the power consumption of the load is limited to be equal to or less than the sum of the allowable maximum output of the fuel cell and the actual output of the power storage device. Thereby, it is possible to prevent the fuel cell from compensating for the shortage of the output of the power storage device beyond its allowable maximum output, and to prevent the fuel cell from being deteriorated and damaged.

  According to the present invention, when the voltage conversion unit does not control the voltage between the fuel cell and the load, that is, when the power storage device or the voltage conversion unit may not output the allowable maximum output, The power consumption of the load is limited to be equal to or less than the sum of the maximum allowable output and the actual output of the power storage device or voltage converter. As a result, it is possible to prevent the fuel cell from compensating for the shortage of the output of the power storage device or the voltage conversion unit beyond its allowable maximum output, and to prevent deterioration or damage of the fuel cell. In addition, the output from the fuel cell and the power storage device or voltage are switched to switch the method of limiting the power consumption of the load depending on whether the voltage conversion unit controls the voltage between the fuel cell and the load or not. The output from the conversion unit can be suitably controlled.

1 is a circuit diagram of a fuel cell vehicle equipped with a fuel cell system according to an embodiment of the present invention. It is a flowchart of the process which calculates the electric power supplied to a motor in the said embodiment. It is a flowchart of the calculation process of the motor output limit value in the said embodiment. It is a flowchart of the calculation process of the assist permissible maximum output in the said embodiment.

A. Embodiment 1 FIG. Configuration of Fuel Cell Vehicle 10 (1) Overall Configuration FIG. 1 shows a fuel cell vehicle 10 (hereinafter referred to as “FC vehicle”) equipped with a fuel cell system 12 (hereinafter also referred to as “FC system 12”) according to an embodiment of the present invention. FIG. 10 is also a circuit diagram. The FC vehicle 10 is basically referred to as a motor unit 20, an FC unit 40, a battery unit 60, and a general control unit 80 (hereinafter also referred to as “general ECU 80” (ECU: Electric Control Unit)). }. Among these components, the FC unit 40, the battery unit 60, and the overall ECU 80 constitute the FC system 12.

  The motor unit 20 generates a driving force for driving the FC vehicle 10 using the driving motor 22 when the FC vehicle 10 is powered. The motor unit 20 generates regenerative power (motor regenerative power Preg) generated by the motor 22 when the FC vehicle 10 is regenerated. ) [W] is supplied to the battery unit 60.

  The FC unit 40 supplies the output (FC power generation output Pfc) [W] generated by the fuel cell 42 (hereinafter also referred to as “FC42”) to the motor unit 20 when the FC vehicle 10 is powered. During regeneration, the FC power generation output Pfc is supplied to the battery unit 60.

  When the FC vehicle 10 is powered, the battery unit 60 supplies output power (battery output power Pbat) [W] from the power storage device 62 (hereinafter also referred to as “battery 62”), which is energy storage, to the motor unit 20. When the FC vehicle 10 is regenerated, the motor regenerative power Preg and the FC power generation output Pfc are stored in the battery 62.

  The overall ECU 80 controls the motor unit 20, the FC unit 40 and the battery unit 60.

(2) Motor unit 20
In addition to the motor 22, the motor unit 20 includes a power drive unit 24 (hereinafter also referred to as “PDU24”), a speed reducer 26, a shaft 28, wheels 30, and a motor control unit 32 {hereinafter referred to as “motor ECU 32”. Also called. }.

  The PDU 24 converts the generated current (FC generated current If) [A] from the FC 42 and the output current (battery output current Ibat) [A] from the battery 62 when the FC vehicle 10 is powered, Is supplied to the motor 22 as a current for driving the motor 22 (motor driving current Imd) [A]. The rotation of the motor 22 accompanying the supply of the motor drive current Imd is transmitted to the wheels 30 through the speed reducer 26 and the shaft 28.

  In addition, the PDU 24 performs AC / DC conversion on the regenerative current (motor regenerative current Imr) from the motor 22 when the FC vehicle 10 is regenerated, and supplies the battery unit 60 with the battery charging current Ibc. The battery 62 is charged by the supply of the battery charging current Ibc.

  The motor ECU 32 controls the operation of the motor 22 and the PDU 24 based on a command from the general ECU 80.

(3) FC unit 40
In addition to the FC 42, the FC unit 40 includes a hydrogen tank 44, an air compressor 46, an FC control unit 48 (hereinafter also referred to as “FC ECU 48”), a backflow prevention diode 50, a voltage sensor 52, and a current sensor. 54.

  The FC 42 has, for example, a stack structure in which cells formed by sandwiching a solid polymer electrolyte membrane between an anode electrode and a cathode electrode from both sides are stacked. A hydrogen tank 44 and an air compressor 46 are connected to the FC 42 by piping. Pressurized hydrogen in the hydrogen tank 44 is supplied to the anode electrode of the FC 42. Further, air is supplied to the cathode electrode of the FC 42 by the air compressor 46. The operations of the hydrogen tank 44 and the air compressor 46 are controlled by the FC ECU 48. An FC power generation current If is generated by an electrochemical reaction between hydrogen (fuel gas), which is a reaction gas, and air (oxidant gas) in the FC 42. The FC generated current If is supplied to the PDU 24 through the current sensor 54 and the diode 50 when the FC vehicle 10 is powered, and is supplied to the battery unit 60 during regeneration. The FC generated current If detected by the current sensor 54 is output to the overall ECU 80 via the communication line 82. Further, the power generation voltage (FC power generation voltage Vf) [V] of the FC 42 is detected by the voltage sensor 52 disposed between the FC 42 and the diode 50, and is output to the FC ECU 48 and the general ECU 80 via the communication line 82. .

  The air compressor 46 is arranged between the motor unit 20, the FC 42 and the battery unit 60, and is configured to be able to supply power from any of the motor unit 20, FC 42 and battery unit 60.

  Although not shown in FIG. 1, the output voltage of each cell of the FC 42 is detected by a voltage sensor (not shown), and the detected value is notified to the FC ECU 48 and the general ECU 80.

(4) Battery unit 60
In addition to the battery 62, the battery unit 60 includes voltage sensors 64 and 66, current sensors 68 and 70, a battery control unit 72 (hereinafter also referred to as “battery ECU 72”), a DC / DC converter 74 and a converter control unit 76. (Hereinafter also referred to as “converter ECU 76”), a VCU 77 (VCU: Voltage Control Unit), a downverter 78, and an auxiliary machine 79.

  The battery 62 is connected to the primary side 1S of the DC / DC converter 74. For example, a lithium ion secondary battery, a nickel hydride secondary battery, or a capacitor can be used. In this embodiment, a lithium ion secondary battery is used. The voltage sensor 64 detects the voltage (primary voltage V1) [V] of the primary side 1S of the DC / DC converter 74 and outputs it to the communication line 82. The voltage sensor 66 detects the voltage (secondary voltage V2) [V] on the secondary side 2S of the DC / DC converter 74 and outputs it to the communication line 82. The current sensor 68 detects the primary side 1S current (primary current I1) and outputs it to the communication line 82. The current sensor 70 detects the current on the secondary side 2S (secondary current I2) and outputs it to the communication line 82.

  The battery ECU 72 monitors the temperature and voltage (battery voltage Vbat) [V] of the battery 62 and protects the battery 62 by limiting or stopping charging / discharging when an abnormality is detected.

  The DC / DC converter 74 is a so-called chopper step-up / step-down DC / DC converter, which boosts the primary voltage V1 and supplies it to the secondary side 2S during power running, and steps down the secondary voltage V2 during regeneration. Supply to the primary side 1S. That is, the battery is generated by the regenerative voltage (motor regenerative voltage Vreg) [V] generated by the motor 22 or the secondary voltage V2 based on the FC power generation voltage Vf of the FC 42 converted to a low voltage by the DC / DC converter 74. 62 is charged.

  Converter ECU 76 controls DC / DC converter 74 based on a command from overall ECU 80 and detection values of voltage sensors 64 and 66 and current sensors 68 and 70. Converter ECU 76 can control FC power generation current If by changing secondary voltage V <b> 2 by the operation of DC / DC converter 74.

  The downverter 78 steps down the primary voltage V1 and supplies it to an auxiliary machine 79 such as an air conditioner or a lamp.

(5) General ECU80
The overall ECU 80 controls the motor ECU 32, the FC ECU 48, the battery ECU 72, and the converter ECU 76 based on the required output of the motor 22 (motor required output Pmot_req) [W] and the required power of the FC unit 40 (such as the air compressor 46). That is, the power (motor supply power Pmot_sup) [W] supplied from the FC system 12 to the motor unit 20 is calculated, and the FC system 12 is operated to realize the motor supply power Pmot_sup. The overall ECU 80 may control other ECUs.

  The overall ECU 80 includes a CPU, ROM, RAM, timer, input / output interfaces such as an A / D converter and a D / A converter, and a DSP (Digital Signal Processor) as necessary. The same applies to the motor ECU 32, the FC ECU 48, the battery ECU 72, and the converter ECU 76.

  The general ECU 80, the motor ECU 32, the FC ECU 48, the battery ECU 72, and the converter ECU 76 are connected to each other through a communication line 82 such as a CAN (Controller Area Network) that is an in-vehicle LAN. These control units realize various functions by input / output information from various switches and various sensors as input to each CPU executing a program stored in each ROM.

(6) Others As various switches and various sensors for detecting the vehicle state, in addition to the voltage sensors 52, 64, 66 and current sensors 54, 68, 70 described above, an ignition switch 90 connected to the communication line 82, an accelerator sensor 92, a brake sensor 94, a vehicle speed sensor 96, and the like.

2. Various Control / Processing (1) Calculation Process of Motor Supply Power Pmot_sup FIG. 2 shows a flowchart in which the FC system 12 calculates the motor supply power Pmot_sup.

  In step S1, when the FC vehicle 10 is in a power running state, the overall ECU 80 calculates a motor request output Pmot_req according to the amount of depression of an accelerator pedal (not shown) detected by the accelerator sensor 92. In step S2, the overall ECU 80 calculates a motor output limit value Pmot_lim [W]. The motor output limit value Pmot_lim indicates the maximum allowable output of the motor 22, in other words, the maximum allowable output that the FC system 12 can supply to the motor unit 20 (motor 22). The calculation process of the motor output limit value Pmot_lim will be described later.

  In step S3, the overall ECU 80 determines whether the motor request output Pmot_req is equal to or less than the motor output limit value Pmot_lim. When the motor request output Pmot_req is equal to or less than the motor output limit value Pmot_lim (S3: Yes), in step S4, the overall ECU 80 sets the motor request output Pmot_req as the motor supply power Pmot_sup as it is. When the motor request output Pmot_req exceeds the motor output limit value Pmot_lim (S3: No), in step S5, the overall ECU 80 sets the motor output limit value Pmot_lim as the motor supply power Pmot_sup.

  The overall ECU 80 calculates the torque command value and the torque limit value by dividing the motor supply power Pmot_sup and the motor output limit value Pmot_lim by the number of rotations [rpm] of the wheel 30, and calculates the torque command value and the torque limit value to the motor. The PDU 24 and the motor ECU 32 of the unit 20 are notified.

(2) Calculation Process of Motor Output Limit Value Pmot_lim FIG. 3 shows a flowchart of the calculation process (S2 in FIG. 2) of the motor output limit value Pmot_lim.

  In step S11, the overall ECU 80 determines whether the converter ECU 76 of the VCU 77 is controlling the secondary voltage V2 (whether it is operating in the V2 control mode). Whether or not converter ECU 76 is operating in the V2 control mode is determined by, for example, the command value of secondary voltage V2 (secondary voltage command value V2com) notified from converter ECU 80 to converter ECU 76 and the actual secondary voltage V2. Judgment is made according to whether or not. Alternatively, the determination can be made by notifying the overall ECU 80 from the converter ECU 76 of the current operation mode.

  The V2 control mode in converter ECU 76 sets the target value of secondary voltage V2 (secondary voltage target value V2tar), and boosts primary voltage V1 so that secondary voltage V2 matches secondary voltage target value V2tar. It is control to do. The secondary voltage target value V2tar is calculated by combining feedforward control based on the secondary voltage command value V2com from the general ECU 80 and feedback control based on so-called PID control (proportional / integral / derivative control). The

  Further, as the operation mode of converter ECU 76 other than the V2 control mode, an I1 control mode and a V1 control mode are set. The I1 control mode and the V1 control mode are controls independently performed by the converter ECU 76 regardless of the secondary voltage command value V2com from the general ECU 80. That is, when converter ECU 76 is operating in the I1 control mode and the V1 control mode, converter ECU 76 does not control secondary voltage V2, but otherwise (primary current I1 or primary voltage V1). Controlled. In other words, the converter ECU 76 does not set the secondary voltage target value V2tar, but sets a primary current target value I1tar or a primary voltage target value V1tar described later.

  In the I1 control mode, for example, when an overcurrent is generated on the primary side 1S, that is, the primary current I1 detected by the current sensor 68 is a threshold (overcurrent threshold THoc) [A] indicating the occurrence of an overcurrent. In the case of exceeding DC, the DC / DC converter 74 is controlled so that the primary current I1 becomes equal to or less than the overcurrent threshold THoc. That is, in the I1 control mode, a target value of the primary current I1 (primary current target value I1tar) is set, and the primary current I1 detected by the current sensor 68 is limited to the primary current target value I1tar or less. The DC / DC converter 74 is controlled.

  In the V1 control mode, for example, for the purpose of controlling the battery output current Ibat supplied from the battery 62, a target value of the primary voltage V1 (primary voltage target value V1tar) is set and detected by the voltage sensor 64. The DC / DC converter 74 is controlled so that the secondary voltage V1 matches the primary voltage target value V1tar.

  Returning to FIG. 3, when the converter ECU 76 is operating in the V2 control mode in step S11 (S11: Yes), in step S12, the overall ECU 80 calculates an assist allowable maximum output Pasi_max [W]. The assist allowable maximum output Pasi_max is an allowable maximum output (rated output) that can be supplied from the battery unit 60. A method of calculating the assist allowable maximum output Pasi_max will be described later with reference to FIG.

  In step S13, the overall ECU 80 calculates the current FC power generation output Pfc. The FC power generation output Pfc can be obtained based on detection values of a voltage sensor and a current sensor (not shown) provided in each cell of the FC 42, for example. Alternatively, it can be calculated on the basis of the voltage (tertiary voltage V3) [V] detected by the voltage sensor 52 and the current (tertiary current I3) detected by the current sensor 54. Note that the FC power generation output Pfc may be zero. The case where the FC power generation output Pfc becomes zero is, for example, a case where a contactor (not shown) for connecting the FC 42 to the FC system 12 is opened. When the contactor is opened, for example, when power generation in the FC 42 is insufficient, such as when the FC vehicle 10 is started, there is a case where the power supply from the FC 42 cannot be normally performed due to the failure of the FC 42.

  In subsequent step S14, the overall ECU 80 calculates the current allowable maximum output of FC 42 (FC allowable maximum output Pfc_max) [W]. In the present embodiment, the FC allowable maximum output Pfc_max is calculated based on the amounts of hydrogen and air supplied to the FC 42. The amounts of hydrogen and air are detected based on values of a hydrogen flow sensor and an air flow sensor (not shown). Alternatively, when the amount of hydrogen and the amount of air are controlled in association with each other, both amounts can be detected by detecting only one amount. In addition to the amounts of hydrogen and air, the voltage and current of each cell constituting the FC 42 can be detected, and the sum thereof can be used as the FC allowable maximum output Pfc_max. Furthermore, the sum of the output reaching the rated voltage or minimum operating voltage of the motor 22 and the output reaching the minimum operating voltage of the air compressor 46 as an auxiliary machine can be set as the FC allowable maximum output Pfc_max.

  In step S15, the overall ECU 80 calculates the power consumption of the air compressor 46 as the auxiliary machine (first auxiliary machine power consumption Pau1) [W]. The first auxiliary machine power consumption Pau1 is measured from a current sensor or a voltage sensor (not shown) installed in the air compressor 46. Alternatively, the determination can be made according to the operation status of the air compressor 46. For example, it may be the expected power consumption calculated based on the air supply pressure and the rotation speed of the air compressor 46.

  In step S16, the overall ECU 80 determines whether or not the FC power generation output Pfc exceeds the FC allowable maximum output Pfc_max. Thereby, it can be determined whether or not an overcurrent has occurred in the FC 42. When the FC power generation output Pfc is equal to or less than the FC allowable maximum output Pfc_max (S16: No), in step S17, the overall ECU 80 calculates the first auxiliary machine power consumption Pau1 from the sum of the assist allowable maximum output Pasi_max and the FC power generation output Pfc. The subtracted value is set as the motor output limit value Pmot_lim (Pmot_lim ← Pasi_max + Pfc−Pau1). When the FC power generation output Pfc exceeds the FC allowable maximum output Pfc_max (S16: Yes), in step S18, the overall ECU 80 calculates the first auxiliary machine power consumption Pau1 from the sum of the assist allowable maximum output Pasi_max and the FC allowable maximum output Pfc_max. The subtracted value is set as the motor output limit value Pmot_lim (Pmot_lim ← Pasi_max + Pfc_max−Pau1). Thereby, even when an overcurrent is generated in the FC 42, it is possible to prevent the FC 42 from being deteriorated or damaged.

  Returning to step S11, when converter ECU 76 is not operating in the V2 control mode (S11: No), in step S19, overall ECU 80 calculates assist output Pasi [W]. The assist output Pasi is the current output of the battery unit 60. The assist output Pasi may be zero. The case where the assist output Pasi becomes zero is, for example, a case where a contactor (not shown) for connecting the battery 62 to the FC system 12 is opened. For example, when the contactor is opened, the power supply from the battery 62 cannot be normally performed due to the failure of the battery 62, or the voltage charged in the battery 62 cannot be controlled when the FC vehicle 10 is regenerated due to the failure of the PDU 24. There may be.

  In steps S20 to S22, the overall ECU 80 calculates the assist allowable maximum output Pasi_max, the FC allowable maximum output Pfc_max, and the first auxiliary machine power consumption Pau1 in the same process as in steps S12, S14, and S15.

  In step S23, the overall ECU 80 determines whether the assist output Pasi exceeds the assist allowable maximum output Pasi_max. Thereby, it can be determined whether or not the battery 62 is overdischarged. When the assist output Pasi is equal to or less than the assist allowable maximum output Pasi_max (S23: No), in step S24, the overall ECU 80 subtracts the first auxiliary machine power consumption Pau1 from the sum of the assist output Pasi and the FC allowable maximum output Pfc_max. The value is set as a motor output limit value Pmot_lim (Pmot_lim ← Pasi + Pfc_max−Pau1). When the assist output Pasi exceeds the assist allowable maximum output Pasi_max (S23: Yes), in step S25, the overall ECU 80 subtracts the first auxiliary machine power consumption Pau1 from the sum of the assist allowable maximum output Pasi_max and the FC allowable maximum output Pfc_max. Is set as the motor output limit value Pmot_lim (Pmot_lim ← Pasi + Pfc_max−Pau1). Thereby, even when the battery 62 is overdischarged, it is possible to prevent the battery 62 from being deteriorated or damaged.

(3) Calculating process of assist allowable maximum output Pasi_max FIG. 4 shows a flowchart of calculating process of assist allowable maximum output Pasi_max {S12 (and S20 in FIG. 3)}. In step S <b> 31, the overall ECU 80 calculates a battery allowable maximum output Pbat_max [W] that is a current allowable maximum output of the battery 62. The battery allowable maximum output Pbat_max can be a rated output of the battery 62, for example. Alternatively, the sum of the output reaching the rated voltage or the minimum operating voltage of the motor 22 and the output reaching the minimum operating voltage of the auxiliary machine 79 can be set as the FC allowable maximum output Pfc_max.

  In subsequent step S32, the overall ECU 80 calculates power consumption of the auxiliary machine 79 (second auxiliary machine power consumption Pau2) [W]. The second auxiliary machine power consumption Pau2 is measured from a current sensor or a voltage sensor (not shown) installed in the auxiliary machine 79. Alternatively, the determination can be made according to the operation status of the auxiliary machine 79. The battery allowable maximum output Pbat_max and the second auxiliary machine power consumption Pau2 may be calculated by the battery ECU 72, and the calculation result may be notified to the overall ECU 80.

  In step S33, the overall ECU 80 calculates the allowable maximum output of the VCU 77 (VCU allowable maximum output Pvcu_max) [W]. The calculation of the VCU allowable maximum output Pvcu_max may be performed by the converter ECU 76 and the calculation result may be notified to the overall ECU 80.

  In subsequent step S34, the overall ECU 80 determines whether or not the VCU allowable maximum output Pvcu_max is less than the difference D between the battery allowable maximum output Pbat_max and the second auxiliary device power consumption Pau2 (Pvcu_max <Pbat_max−Pau2 = D). . When the VCU allowable maximum output Pvcu_max is less than the difference D (S34: Yes), in step S35, the overall ECU 80 sets the VCU allowable maximum output Pvcu_max as the assist allowable maximum output Pasi_max (Pasi_max ← Pvcu_max). When the VCU allowable maximum output Pvcu_max is greater than or equal to the difference D (S34: No), in step S36, the overall ECU 80 sets the difference D between the battery allowable maximum output Pbat_max and the second auxiliary device power consumption Pau2 as the assist allowable maximum output Pasi_max. Set (Pasi_max ← Pbat_max-Pau2).

3. As described above, according to this embodiment, when the converter control unit 76 of the VCU 77 is not operating in the V2 control mode (S11: No in FIG. 3), that is, the VCU 77 has a VCU allowable maximum output. When there is a possibility that Pvcu_max is not output, the motor output limit value Pmot_lim is set to be equal to or less than the sum of the assist output Pasi and the FC allowable maximum output Pfc_max (S24). As a result, it is possible to prevent the FC42 from compensating for the shortage of the output of the VCU 77 beyond the FC allowable maximum output Pfc_max, and to prevent the deterioration or breakage of the FC42. Further, even when the converter control unit 76 is not operating in the V2 control mode (S11: No in FIG. 3), the maximum power can be supplied from the FC 42 and the VCU 77, so that the power consumption of the motor 22 is more than necessary. Thus, the operation performance of the motor 22 can be improved. In particular, in the case of the motor 22, even when the VCU 77 does not control the voltage (secondary voltage V2) between the FC 42 and the motor 22, the maximum power can be supplied from the FC 42 and the VCU 77. It is possible to avoid that the torque is reduced more than necessary, and to improve the drivability of the FC vehicle 10. Furthermore, since the calculation method of the motor output limit value Pmot_lim is switched between when the VCU 77 controls the secondary voltage V2 and when it is not controlled, the output from the FC 42 and the output from the battery unit 60 are preferably controlled. can do.

  In this embodiment, the overall ECU 80 determines the first auxiliary machine power consumption Pau1 from the sum of the allowable maximum allowable output Pasi_max and the FC power generation output Pfc when the VCU 77 is operating in the V2 control mode (S11: Yes in FIG. 3). The motor output limit value Pmot_lim is set to be equal to or less than the value obtained by subtracting (S17), and when the VCU 77 is not operating in the V2 control mode (S11: No), the sum of the assist output Pasi and the FC allowable maximum output Pfc_max The motor output limit value Pmot_lim is set so as to be equal to or less than the value obtained by subtracting the first auxiliary machine power consumption Pau1 (S24). Thereby, even when the air compressor 46 that receives power supply from between the motor unit 20 and the FC 42 and the battery unit 60 is provided, the power consumption of the air compressor 46 is secured and the FC 42 and the battery 62 are more reliably protected. Can do. In particular, the power consumption of the air compressor 46 with relatively large power consumption can be secured, the air compressor 46 can be driven stably, and the FC 42 and the battery 62 can be more reliably protected.

  In this embodiment, when the VCU 77 is operating in the V2 control mode (S11: Yes in FIG. 3), the general ECU 80 determines that the FC power generation output Pfc is higher than the FC allowable maximum output Pfc_max (S16: Yes). The motor output limit value Pmot_lim is set using the FC allowable maximum output Pfc_max instead of the power generation output Pfc (S18). Further, when the VCU 77 is not operating in the V2 control mode (S11: No), the overall ECU 80 determines that the assist is permitted instead of the assist output Pasi if the assist output Pasi is higher than the assist allowable maximum output Pasi_max (S23: Yes). A motor output limit value Pmot_lim is set using the maximum output Pasi_max (S25). Thus, even if the actual output of the FC 42 or VCU 77 becomes transiently higher than the allowable maximum output (FC allowable maximum output Pfc_max, assist allowable maximum output Pasi_max), the FC 42 or the battery 62 can be protected.

B. Modifications It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the contents described in this specification. For example, the following configuration can be adopted.

  In the said embodiment, although FC system 12 was mounted in FC vehicle 10, the object which mounts FC system 12 is not restricted to a vehicle. For example, it can also be used for ships and airplanes. Alternatively, it can be used as a household power source.

  Moreover, in the said embodiment, although the motor 22 for driving a vehicle, the air compressor 46, etc. were used as load, this invention is applicable also to other loads. Furthermore, a configuration in which power is supplied to only one of the motor 22 and the air compressor 46 is also possible.

  In the above embodiment, the calculation formula for the motor output limit value Pmot_lim is switched between when the VCU 77 operates in the V2 control mode and when it operates in the I1 control mode or the V1 control mode. I can't. For example, even when the VCU 77 is not operating normally for some reason, the motor output limit value Pmot_lim can be calculated as in the I1 control mode and the V1 control mode. In this case, whether or not the VCU 77 is operating normally can be determined using, for example, a comparison result between the secondary voltage command value V2com calculated by the overall ECU 80 and the secondary voltage V2 detected by the voltage sensor 66. it can.

  In the above embodiment, the VCU 77 is provided between the motor unit 20 and the battery 62, but the present invention can also be applied to a configuration that does not use the VCU 77. That is, the motor output limit value Pmot_lim can always be set within the sum of the FC allowable maximum output Pfc_max (S14 and S21 in FIG. 3) and the current output of the battery 62 (battery output Pbat) [W].

  In the above embodiment, the output limit of the FC 42 is performed using the FC allowable maximum power Pfc_max [W]. However, based on the current-voltage characteristics of the FC 42, the allowable maximum value of the FC power generation current If (FC allowable maximum current If_max) [A ] Can also be used to limit the output.

10 ... Fuel cell vehicle 22 ... Motor (load)
42 ... Fuel cell 46 ... Air compressor (auxiliary machine)
60 ... Battery unit 62 ... Battery (power storage device)
77 ... VCU (voltage conversion unit) 79 ... auxiliary device 80 ... overall ECU (load control unit) Pasi ... assist output Pasi_max ... assist allowable maximum output Pau1 ... first auxiliary device power consumption Pau2 ... second auxiliary device power consumption Pbat_max ... battery Allowable maximum output Pfc ... FC power generation output Pfc_max ... FC allowable maximum output Pmot_sup ... Motor supply power
Pvcu_max ... VCU allowable maximum output Vbat ... battery voltage Vf ... FC generated voltage V1 ... primary voltage V2 ... secondary voltage

Claims (1)

A fuel comprising: a fuel cell that supplies power to a load; a power storage device that is connected to the load in parallel with the fuel cell and supplies power to the load; and a load control unit that controls power consumption of the load A battery system control method comprising:
The load control unit does not control the voltage between the fuel cell and the load, and when controlling the current or voltage on the power storage device side from the load,
Calculating the maximum allowable output of the fuel cell;
Calculate the actual output of the power storage device,
Calculate the sum of the allowable maximum output of the fuel cell and the actual output of the power storage device,
The method of controlling a fuel cell system, wherein power consumption of the load is limited to be equal to or less than a sum of an allowable maximum output of the fuel cell and an actual output of the power storage device.

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